Very true. Back in the late-80s or early-90s I went on the medically supervised Medifast Diet (liquid diet, ultra-low-calorie, ultra-low-fat). I opted to do it because I was able to do it for free by being part of a drug study.

The drug in question was Actigall, which is used to dissolve gallstones. The study started out with the premise that eating a very low fat diet causes people to develop gallstones. What they wanted to see was if giving a person Actigall at the same time that they followed a very low fat diet would prevent gallstones from occurring. I don't know how many people were being enrolled in the study, but of course we were in double-blind cohorts, with some of us getting a standard dose of Actigall, some of us getting a reduced dose of Actigall, and some of us getting a placebo.

To be accepted for the study you had to first undergo an ultrasound of your gallbladder to make sure you didn't already have stones. My gallbladder was fine, so I was accepted into the program, which lasted for 16 weeks.

I started out at 330 pounds, and after 16 weeks of a 500-calorie-a-day low-fat diet my weight dropped to 264 (which I promptly gained back and then some once I began eating solid food again). I also developed gallstones! Sure enough, the follow-up ultrasound after the 16 weeks showed that I now had gallstones.

They were not large stones, more like sand, but definitely there. So either Actigall didn't work as a preventative, or I was on the placebo or the reduced dose. At any rate I was given a prescription for a free year's supply of Actigall to dissolve the stones, and I never had a gallbladder problem again until it began acting up in 2007, but I still have not had it out. These days I take milk thistle to control gallbladder issues, and I can tell if my milk thistle runs out and I have forgotten to get more, I start getting twinges again!

But it all began with the super-low-fat Medifast diet. The doctors running the study said that gallstones are a classic side effect of very low fat eating.